Fix UT for duplicate name args test case

The test is intended for testing duplicate name arg but
test raised mandatory_args error due to absense of
--cluster-template arg, so test is now updated to raise
DuplicateArgs Exception.
Introduced in: https://review.openstack.org/#/c/434411/

Change-Id: Ieee8bfebfb2c0d03d953550e545bccbdee42e688
Implements: blueprint positional-name

magnumclient/tests/v1/shell_test_base.py

@@ -51,6 +51,12 @@ class TestCommandLineArgument(utils.TestCase):
         ".*?^Try 'magnum help ",
         ]
 
+    _duplicate_name_arg_error = [
+        '.*?^usage: ',
+        '.*?^error: (Duplicate "<name>" arguments:)',
+        ".*?^Try 'magnum help ",
+        ]
+
     _deprecated_warning = [
         '.*(WARNING: The \-\-[a-z\-]* parameter is deprecated)+',
         ('.*(Use the [\<\-a-z\-\>]* (positional )*parameter to avoid seeing '

magnumclient/tests/v1/test_clusters_shell.py

@@ -14,6 +14,7 @@
 
 import mock
 
+from magnumclient.common import cliutils
 from magnumclient import exceptions
 from magnumclient.tests.v1 import shell_test_base
 from magnumclient.tests.v1 import test_clustertemplates_shell
@@ -305,8 +306,11 @@ class ShellTest(shell_test_base.TestCommandLineArgument):
 
     @mock.patch('magnumclient.v1.clusters.ClusterManager.create')
     def test_cluster_create_failure_duplicate_name(self, mock_create):
-        self._test_arg_failure('cluster-create foo --name bar',
-                               self._mandatory_arg_error)
+        self.assertRaises(cliutils.DuplicateArgs,
+                          self._test_arg_failure,
+                          'cluster-create foo --name bar '
+                          '--cluster-template xxx',
+                          self._duplicate_name_arg_error)
         mock_create.assert_not_called()
 
     @mock.patch('magnumclient.v1.clusters.ClusterManager.delete')